This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project will use Long Evans strain, with chronic Platinum/Iridum electrodes implanted in brain. Electrodes will be removed prior to scan, following perfusion with the contrast agent. Our project aims to understand the mechanisms of deep brain stimulation in the treatment of Parkinson's disease using a 6-OHDA rat model. We implant stimulating electrodes in the subthalamic nucleus (STN), and recording electrodes in the globus pallidus externa (GPe) and substantia nigra pars reticulata (SNr) of the rats. The neural recordings are then correlated with behavioral studies to observe changes in neuronal firing during effective stimulation at different rates and patterns of stimulation. Implanting electrodes accurately in the various targets is a challenging task, and we hope to use MR microscopy to determine whether our stimulation and recording electrodes are indeed in the correct locations. We also aim to correlate the MR studies with histological analysis of the brain tissue. This will allow us to validate our results, as well as aid us in future surgeries to better target the various positions in the rat's brain.